1MBEGROWTHANDINSTRUMENTATION

2MBEGROWTHANDINSTRUMENTATION MBE GROWTH AND INSTRUMENTATION Thesis Proposal Outline for the Degree of Master of Science Major Professor Dr. Terry Golding Ph.D, University of North Texas

3MBEGROWTHANDINSTRUMENTATION MBE GROWTH AND INSTRUMENTATION n MBE growth. n RHEED. n Research Method. n References

4MBEGROWTHANDINSTRUMENTATION MBE Growth n Introduction. n Description of MBE system and functioning. n Advantages and applications.

5MBEGROWTHANDINSTRUMENTATION MBE GROWTH-INTRODUCTION MBE GROWTH-INTRODUCTION Schematic illustration of basic evaporation process for MBE

6MBEGROWTHANDINSTRUMENTATION MBE GROWTH DESCRIPTION AND FUNCTIONING Schematic cross section of an advanced three- chamber UHV system designed for MBE growth

7MBEGROWTHANDINSTRUMENTATION MBE GROWTH APPLICATIONS AND ADVANTAGES n Growth of electronic and photonic devices such as solar cells, diode lasers, LEDs and heterojunction bi-polar junction transistor. n Slow growth rate of ~1μm. n Reduced temperatures of about o C n Reduced handling requirements of toxic materials such as As. n The ability to abruptly cease or initiate molecular beams producing hyperabrupt surfaces. n Facility of in situ analysis during growth.

8MBEGROWTHANDINSTRUMENTATION RHEED - INTRODUCTION n Powerful tool for in situ analysis during the growth process. n Used to calibrate growth rates. n Observe removal of oxides from the substrate. n Calibrate the substrate temperature. n Monitor the arrangement of surface atoms. n Give a beedback on surface morphology.

9MBEGROWTHANDINSTRUMENTATION RHEED PRINCIPLE OF OPERATION RHEED Gun setup for MBE growth

10MBEGROWTHANDINSTRUMENTATION RHEED - OSCILLATIONS Video tape stills of Sn-modified Rheed patterns from As- stabilized (001) GaAs at 550 o C: (a) Without Ga flux (b) Immediately after applying Ga flux.

11MBEGROWTHANDINSTRUMENTATION RHEED OSCILLATIONS PLOT Recorder traces of intensity as a function of time at the point A

12MBEGROWTHANDINSTRUMENTATION RHEED – INTENSITY VARIATIONS Illustration of RHEED spot oscillations during the growth of a monolayer

13MBEGROWTHANDINSTRUMENTATION RHEED PATTERNS – AN EXAMPLE RHEED patterns and the corresponding electron micrographs of (110) GaAs grown using MBE : (a) GaAs heated in vaccum to 580 o C for 5min. (b) 150 o A layer of GaAS on the surface of (a). (c) 1µm of GaAs deposited on surface of (a )

14MBEGROWTHANDINSTRUMENTATION MBE – RESEARCH METHOD n Experimental. n Video RHEED Intensity Measurement System. n LabVIEW, frame grabber cards. n Specview. n Spectramass PC2000.

15MBEGROWTHANDINSTRUMENTATION MBE - REFERENCES n Oscillations in the Surface Structure of Sn-doped GaAs during growth by MBE [Surf. Sci. 103, L90 (1981)] by J.J.Harris, B.A.Joyce and P.J.Dobson. n A.Y.Cho, J. Vac. Sci. Technol. 8, S31 (1971). n Molecular Beam Epitaxy of III-V Compounds: Technology and Grwoth Process, by Klaus Proog. Ann. Rev. Material Sci n W.Braun. Applied RHEED. Reflection High-energy Electron, Diffraction during Crystal Growth Springer Tracts in Modern Physics, n A. Y. Cho, Key papers in Applied Physics – Molecular Bem Epitaxy, AIP Press n n pter pter

16MBEGROWTHANDINSTRUMENTATION QUESTIONS???

17MBEGROWTHANDINSTRUMENTATION Thank you…..